1. Field of the Invention
The present invention relates to a structure of touch display panel and, more particularly, to an in-cell touch display panel system using metal wires to connect with sensing electrodes.
2. Description of Related Art
A conventional touch display panel includes a touch panel and a display unit overlapped with the touch panel. The touch panel is configured as an operation interface. The touch panel is transparent so that an image generated by the display unit can be viewed directly by a user without being sheltered by the touch panel. Such well known skill of the touch panel may increase additional weight and thickness of the touch display panel, and may further reduce the light penetration rate, and increase reflectance and haze of the touch display panel.
On-cell and in-cell touch technologies were invented to overcome the drawbacks of traditional touch technology described above. The on-cell technology is to dispose sensors on the back side of a color filter substrate to form a completed color filter substrate. One of the on-cell touch technologies is provided to dispose touch sensors on a thin film and then bond the thin film onto the upper one of the two substrates.
The in-cell technology is to dispose the sensors within the LCD cell structure. Currently, there are resistive, capacitive and optical three primary in-cell touch technologies, wherein the resistive touch technology employs two conductive substrates and the voltage variation of a common layer between the two substrates for determining a touch position on the touch display panel.
The in-cell touch technology is provided to integrate the touch sensor within the display unit so that the display unit is provided with the ability of the touch panel. Therefore, the touch display panel does not need to be bonded with an additional touch panel so as to simplify the assembly procedure. Such skill is generally developed by TFT LCD manufactures.
There is older touch control technology known as out-cell, which is typically applied to the resistive and capacitive touch panels. The out-cell touch technology is provided to add a touch module onto a display module. The touch module and the display module can be manufactured by the two separate parties.
However, for all the in-cell, on-cell and out-cell touch technologies, they all need a transparent sensing electrode layer to be configured on an upper or lower glass substrate, which not only increases the manufacturing cost but also complicates the manufacturing process, and which may also lower the aperture ratio and thus need to increase the strength of backlight, resulting in huge power consumption which is disadvantageous to make the mobile device compact. Furthermore, because the distance between the transparent sensing electrode layer and the common electrode (Vcom) layer of the LCD display panel is very tiny, the capacitance formed by the finger and the transparent sensing electrode layer is much smaller than that formed by the transparent sensing electrode layer and the common electrode (Vcom) layer when performing touch sensing with the transparent sensing electrode layer. Therefore, for calculating the touched coordinate by using the touch sensing of the transparent sensing electrode layer, the variation of values obtained from different sensing electrodes becomes too small to distinguish, which is disadvantageous to coordinate calculation. That is, due to the capacitance between the transparent sensing electrode layer and the finger being much smaller than that between the transparent sensing electrode layer and the common electrode (Vcom) layer, the capacitance between the transparent sensing electrode layer and the finger is likely to be influenced by the capacitance between the transparent sensing electrode layer and the common electrode (Vcom) layer, resulting in decreasing the accuracy of touch sensing. Therefore, it desired for the aforementioned touch display panel system to be improved.